System and method for fitting



5 Sheecs--Shec-zkl l C. E. RUDIGER SYSTEM AND METHOD FOR FITTING HEARINGAIDS June 6, 1950 Filed Sept. 22, 1945 sa//Jag L{/ ssa? gun/Joa#INVENTOR (af/ Rua/7er BY /mf// s ATTORNEYS JUN 6, 1950 c. E. RUDIGER2,510,480

SYSTEM AND METHOD FOR FITTING HEARING AIDS Filed Sept. 22, 1945 5Sheets-Sheet 2 u? l 4 6 769 4g /w 5 5 /ma .e 3 4 .s

/eguency /n [yc/e5 per jew/7d :lune 6, 1950 C. E. RUDIGER SYSTEM ANDMETHOD FOR FITTING HEARING AIDS Filed Sept. 22, 1945 5 Sheets-Sheet 3NSN IVENTOR (ar/ f/Pua/l' er BY ATTORNEYS June C. E. RUDIGER SYSTEM ANDMETHOD FOR FITTING HEARING AIDS Filed Sept. 22, 1945 5 Sheets-Sheet 4ATTORN EYS l c. E. RUDIGER SISTEM AND METHOD FOR FITTING mamme AIDSFiled sept.. 22, 1945 June 6, 1950 l 5 Sheets-Sheet 5 Sm. QN

Sa 12a ul $9.0 b21/40a INVENTOR:

/ 7 #far/R000 er EY/d v ATTORNEYS Patented `lune 6, 1950 UNITED STATES`PATENT OFFICE 2,510,480 SYSTEM AND MET'OFR FT'TG HEARING AIDS arlRudiger, Hawthorne, N'. Ya, assignor to Sonotone Corporation, Elmsford,N. Y., a corporation of New York Application September 22, 1945, SerialN. 618,029

4 Claims. 1

This invention relates to systems and methods for fitting hearing aids;and it has among its objects a novel and effective system on the basisof which the audiometric measurement of the hearing loss of a deafenedperson makes it possible to determine which of a mumber of receivers ofknown performance and frequency re' sponsc clflaracteristics and, incombination with the receiver, which of several tone control set= tingsof any available hearing aid amplifier sys*- tems will be most suitableto compensate for the hearing deciencies of the user. Y

The foregoing and other objects of the inven-v tion will be bestunderstood from the following description of exemplifications thereof,reference being had to the accompanying drawings wherein Fig. 1 is anaudiogramof a hard of hearing person whose hearing impairment isrepresenta-A tive of the predominantly nerve type; l

Fig; 2 is an audicgram of a hard of hearing person whose hearingimpairment is representa' tive of the predominantly obstructive type;

Fig. 3 is a curve diagram'showin-g the frequency responsecharacteristics of a series of different receivers with which a givenhearing aid amplifier circuit is designed to operate;

Figs. 4 to 7; inclusive,- show the overall frequency response of onetype of commercial hearing aid when operating in combination with thefour different types of receivers,v the characteristics of which areshownin Fig. 3;

Fig. 8 is a plan View of a slide scale designed for cooperation withaudiograms of the type shown in Figs.- 1 and 2 for indicating which eai`of the individua-l having the hearing impairment shown in suchaudiograzn should preferably be tted with ahearing aid receiver,` andwhether he would preferably use an air conduction receiver or a boneconduction receiver;

Fig, 8A is anend view of the slide scale of Fig: 8;

Fig. 9 is a plan view of a chart designed for cooperation with anaudiogram of the type shown in Figs; 1 and 2 for indica-ting which ofthe res ceivers, the characteristics of which are shown in Fig. 3, andwhich tone control setting of a hearing aid amplifier having the overallresponse characteristics shown in Figs. 4 to 7, will provide bestcompensation for the given hearing impair= men-t;

Fig. 10 is a part of the audiogram of Fig. 1 with a part o'f the chartof Fig. 9 superimposed thereoiij Fig'. l1 a part of the aiidiograr'n fFig. 2 with a part of the cliart ff Fig'. 9 superimposed on it;

Fig; 12 is a plan view of a chart designed for cooperation with anaudiogram of the type shown in Figs; 1 and 2 for indicating which typesof sounds the user will have diiiiculty in hearing.

Referring to Fig. l, which is a typical audiogram of a person sufferingfrom a predominantly nerve-type hearing impairment, full-line curve 2|indicates the overall hearing loss for the right ear; and full-linecurve 22 indicates the overall loss for the left ear,- both measuredwith a standard audiometer and a standard air conduction receiver, whiledotted-line curves Zl-l and 22-1 show the loss in hearing for boneconduction for the right and left ears, respectively, when measured witha standard audiometer and equipped with a standard bone conductionrceiver.

In order to provide a person of defectivey hearing with an effectivehearing aid, its amplifying characteristics should be such as tocompensate for the loss indicated in the audiogram, without subjectinghim to undesired nervous reactions or tiring him. The overallamplification and frequency response characteristics of a hearing aidare determined by the integrated response characteristics ofthemicrophone, amplifier and the receiver and the different tone` controlsusually provided in the amplifier.-

The frequency response curves of Fig. 4 show the overall responsecharacteristics of a standard commercially-available hearing aidequipped with an air conduction receiver having the fresuency responsecharacteristics shown by curve l9-L of Fig: 3. In the curves of Fig. 4,the upper full-line curve 3IA- represents the overall frequency responseof the hearing aid with its receiver referred to above when its tonesetting is set to give the maximum overall amplication; The hearing aidin question has a tone control which makes it possible to cut its 10Wfrequency response over a continuous range extending over six principalsettings A, B; C; D,- E, and F, respectively; curve 3|F of Fig. 4representing the overall frequency response of this hearing aid receivercombination with the tone control set for the setting F in which the lowfrequency response is cut to a maximum.

lEn Fig.- 5 the two analogous curves 32--A, 32--F represent the overallresponse of the same hear ing aid in combination with a receiver havingthe frequency response I'G-W of Fig. 3;

In Fig. 6; the two analogous curves 33-A; 3321i represent the overallresponse of the same hearing aid in combina-tion with a receiver havin'gthe frequency response lll-H of Fig; 3;

In Fig: 7,- the two analogous curves :il-1A;

34 F represent the overall response of the same hearing aid incombination with a receiver having the frequency response I I-IH of Fig.3.

A hearing aid designed to operate with overall response curves and tonecontrols of the type referred to above is described in U. S. ShapiroPatent 2,327,320.

If now, a person having a hearing impairment of the type shown in theaudiogram of Fig. 1, is to be tted with a hearing aid having theresponse characteristics of the type shown by the curves of Figs. 3 to7, the slider scale arrangement of Fig. 8 is employed to determinefirst,r

which ear is to be fitted, and second, whether air conduction or boneconduction receivers are to be employed. The slide scale of Fig. 8 hastwo relatively movable slide members 4|, 42. Slide member 4| is shownprovided with a main scale 4 I l which is a replica of the hearingv lossscale of the audiogram charts in connection with which they are used,such as shown in Figs. 1 and 2.`

In the chart of Fig. 1, the line of zero hearing loss, that means theline of normal hearing, is shown at the top of the chart, and thehearing loss is indicated in decibels. In the slide scale Il l', thezero indication of the hearing loss is at the bottom of the scale.

A part of the main scale 4| I of slide member 4! has an additionalregion mark M Z which serves as the ear selector mark andis so placedthereon that when the zero line of its scale 4! is placed over theaudiogramchart of Fig. 1, opposite the air-conduction threshold ofhearing of the poorer ear of the given individual, at a selected portionof the speech frequency spectrum corresponding to average hearing, suchas about 1500 cycles per second (C. P. SJ, and part of the scale Mextending above the ear selector region mark 4! 2 overlaps or crossesthe zero line of the audiogram, it is preferable that the hearing aidshould be fitted to the other ear which has a lesser hearing loss. Theregion mark M Z corresponds, in effect, to an indication that if theair-conduction hearing loss of the poorer ear is greater than indicatedby the region mark M Z, it is better to lit a hearing aid to the betterear because tting the better ear will give greater benefits, taking intoaccount the distance-range of hearing, the servicing of the instrumentand economy.

For the particular instrument in connection with which the system heredescribed has been designed, it has been found that if theair-conduction loss of the poorer ear at 1500 C. P. S. is greater than'70 decibel it is preferable to t the instrument to the better ear.Thus, if the slide scale 4! is applied to the audiogram of Fig. 1, withthe zero mark of slide scale'M- i opposite the point of theair-conduction threshold of hearingrof the poorer ear shown by curve 22at 1500 C. P. S., the region mark 4| 2 of scale M will be below the zeroline of the audiogram and this will be an indication that the better*Year, which, in the present case, exhibits only a hearing loss of about60 db. at this frequency, isl to be fitted.

The use of the slider scale M with its ear selector mark 1 2 issimplified by making it of transparent sheet material so that when it isplaced over an audiogram such as shown in Figs. 1 and 2, the audiogramcurves and data are visible. Furthermore, the entire upper part of theslider scale lli-i extending above the region mark( M is given adistinguishing color, indicated by the slanted dash shade lines so thatthe colored transparent upper part of the scale l!! shall serve as theear selector region m'ark 4I` 2- As indicated in Figs. 8, 8A, thetransparent slider member il is shown arranged as a guidev for the otherslide member 42, which is likewise made of transparent sheet material.The other slide member 42 has a scale 42 I which is shorter than thescale d 1 of the other slider, and is so related thereto, that the fulllength of scale ti2 i indicates the maximum bone conduction loss ofhearing at which an individual could be effectively fitted with theparticular type of boneconduction instrument, the full length of theother scale di-i of the other slide member 4| representing the maximumair-conduction loss of hearing at which an individual could be fittedwith an air-conduction instrument. Ihe slide scale M has a graduationcorresponding to the graduation of the main hearing loss scale 4| I ofthe slide member di, the spaces between the graduation marks of scale42-1 or its divisions being proportionately reduced.

The two slider members d l 42, with their scales li! M serve todetermine whether the ear which is to be iitted will be better served byair conduction or bone conduction. To this end, the zero line of thescale 42 of slider 42, or the slider part extending below the zero lineof scale n dil-4, and shown by the area with the slanted dash shadelines @2 2, serves as the bone conduction Selector region mark, so thatwhen the scale #2 2 is placed over the audiogram with a graduation ofits scale corresponding to the air conduction loss of hearing on theZero line of the audiogram at the average hearing frequency, such as1500 C. P. S., and the bone conduction threshold of hearing of the earwhich is to be tted falls below the zero mark of scale 42 or within thearea of the bone-conduction `selector region 2 2, this is an indicationthat the user should be tted with an air-conduction instrument.

When using a slider arrangement of the type described invconnection withFigs. 8, 8A, one may proceed, in connection with the case represented bythe audiogram of Fig. 1, as follows:

Having previously determined that the better ear of the individualshould be fitted, the zero mark of slide scale l i is placed over theaudiogram chart of Fig. 1, the curve of the air conduction threshold ofhearing 2l of the ear which is to be fitted at the frequency of hisaverage hearing ability, at about 1500 C. P. S. After noting on scale Mof slide member 4! crosses the zero line of the audiogram at 58, theother slide member 42 is moved till its scale likewise crosses the zeroline at the same numerical indication, namely, This is indicated in Fig.1 by superimposing thereon parts of the two scales M i, M in thealignment just described.

If now, the bone conduction selector mark @2 2 of scale @2 2 isintersected by the curve of the bone-conduction threshold curve 2l l ofthe ear which. is to be iitted., then this is an indication that airconduction should be fitted, the hearing loss being primarily of thenerve type rather than of the obstructive type. In general. these scaleshelp to determine whether the bone conduction loss is so great inrelation to the air conduction loss as to indicate that it is better tofit the ear in question with an air conduction instrument.

By using the slide scale arrangement in an analogous manner inconnection with audiogram chart of Fig. 2, it may be readily determinedthat in that case likewise the better ear is to be tted. Furthermore, byadjustably setting the two slide mules M l., -.42-:| on `the :audiogramvdata :ci Fig. 2 in the manner just described in connection with 1,it'will beriound that :bone conduction selector :mark t2-L2 offthe'slide member #12 rnot crossed by the bone-conduction threshold linecurve 2li-l of the `betterrear which-is to be rfltted, indicating thatthe user .should be tte. with a bone Vconduction instrument.

summarizing, lthe slider scale loi :the type rdesmfibed above connection'with Figs. '8 .and '8A and designed to form part-of azsystemiforHitting hearing aid instruments of predeterminedcomponmrt and overallperformance characteristics inaccordance with the hearing loss'of theuser, as `:indicated by yaudiometric `.curves of a .hearing aid on anaudiogram chart Vhailing .a .frequency scale .and a hearing loss scale,embodies the iollowing A.important features:

.One slider scale member is ia scale correspondingto the loss scale ofItfe audiogram chart and an ear selector mark is so placed on its lossscale that when this scale member is placed :in .a predeterminedposition on the audiogramichart, lthe relationship of the selector markto the `,curve data'of the audiogram chartwill indicate'whether the.hearing aid instrument is to be fitted to the better ear orto thepoorerea'r-of the user.

`The slider Iscale has an addi-tional vslider scale member having ascale shorter than the `hearing loss scale l.of the 'audiograrm socorrelated to the performance characteristics of the instrument 'of thehearing aid andthe audiometric curves of the audiogram chart, that ywhenthis :scale member is placed in a 'predetermined position on theaudiogram chart, the relationship of the 'elements of the vadditionalscale to the curve data [of -the audiogram chart will indicate 'whetherthe user is to be 'tted with abone conduction instrument or an airconduction instrrment.

The two slider scale members are made transparent sheet material :sothat they may `be superimposed on the aud-iogram chart without obscuringthe data of the audiogram chart, yand one slider is movable to the other.slider member so that the scales of the two sliderrmemb'ers 'may becorrelated. vto each other .and `Ato the data of the audiogram chart'for determinmg whether the hearing aid is to be fitted to the betterear or 4to the poorer ear lof the user as Well ras "to indicate whetherthe user is Vvto 'be tted with a bone conduction instrument or an air:conduction instrument.

In order to vmake it possible 4to determine, `with a 'hearing aidampliiier instrument having tone controls of the type described above,which :of the various receivers and which tone controls should be used,there is provided `an additional fitting e shown in 9. :fitting guide islikewisel made of `a plastic transparent sheet member;7 so that when isfsuperimg sed fon the audiogram, its curves markings will lbe clearlyseen. The chart of 9 has `a vertical line corresponding to the ESO-cycleline of the audiogram, "her vertical line corresponding to the 23904;.line of the audiogram. Et been f'orud hat the region between 'the 'twofrequencies is a good criterion fordetermining in a general manner whichtype of instrument and what type of controls will fit best, :or r,willfcompensate best for the vnearing impairment of the user.

In other words, the two lines marked '500 and 2000 .of lig. 9 correspondtothe ladjacent `boundaries vof the frequency range which it has beenfound practical to use for detenmining the instrument fand the :type ofcontrols which fare likely vto fbest ,-t .the fuser. The lower frequencyboundary rline, in the present case, the rline .500,`

has ithereon :a 'Window vmark 53 :which 4`is to be placedonthecorresponding frequencylineof the audiogram .of the individual, -onthe threshold point :of the .fair .conduction loss curve 'or 'boneconduction :loss .curve, `depending on whether he has to be `fitted-with:an airfor ybone conduction instrument. :In the'case shown,'theflowerboundary :line L; the 500 'cycle line, and when used inconnection with the au'diogr-am of Fig. 1,'the window mark 5S is placedover -the -vthreshold curve 2.! at .theOG cycle frequency.

The two divergent lines 54, extending ffrom the Window mark 5-3 of thechartof Fig. 9 .are 'so placed thereon :as to provide fboundary ylinesvbetween-cases of hearing loss as shown in thefaudiograms requiring'instruments which provide -predominant amplification in the low`Vfrequency rangeor in the `high frequency rang'e'or reuuiring.

more or less uniform amplincationover the .ene tire frequency range.Thus, the boundary line 5 'is the lower 'boundary line for the:audiogram area requiring 'low frequency amplification, the boundaryline A55 'is the upper boundary line for the audicgram area requiringhigh vfrequency amplification, ywhile the audiogram .area extendingbetween the two boundary lines 54, 55 defines the region Vbest served bysubstantially uniform overall amplcation.

In the region Aof 'the chart of Fig. v9 extending between vthe tw@`frequency boundary llines 5 l, -5-2, 1ere are Ashoe-.fn two verticalcolumns yOJegends indicating fthe type of receivers that are to Ebefitted. In :the case shown, the Vcolumn headed by .mark A indicates thedifferent types of air con-duction receivers and the column iheaded bythe ina-rh -B vindica-tes the .different types of bone conductionreceiver-s. There also shown `in the chart an "additional T heading thetone controls 'ci the different instruments which are to Ybe fitted.

Fig. lil which contains the threshold curve v2s] of the audiograrn VofFig. -l has Asuperimposed thereon the marl; linesoi Fig. 9 -to indicatehow the particular user will `be fitted with a hearing aid by the:indications @n the chart 'of Fig. 9. It will be seen that 'si-nce `:thethreshold line 2l -is the fourre he ybe iitt-ed with an a-ir ctionreceiver ISB-W and an instrument with a tone control setting Ccorresponding to the instruments tone control settings 4'described abovein connection with the char-ts A0f S 'to i?.

Fig. :ll is an audiograrn correspond-ing to the audiograui of 2, butshowing only .the loss curve 243-! of the ear is 'to be fitted, and ithas chart marks oi la? g. El superimposed fthere on. As indicatedthereon, since the threshold curve 24%5 .is between the boundary lines54, 55

f iitting cha-rt of Fig. 9, the ear 'should he fitted vwith a boneconduction instru-nent 2--W and an yin.strrnruentwith. a tone settingrmii-lil In. other word using the chart `of Fig. 9., its window isplacedcver the A505icycle point curve of the ear and type of hea-r. chis to be jtted. If .the threshold curve of hear-ing extends above theboundary line 54, the ear will be tted either with .an .air conduction'or bone condo. tin .instrument indicated above undary 5.a and with atone control likewise indicated above the boundary line .54.

If the threshold curve of hearing -of the ear which is to be fittedextends between the two boundary lines 54, 55 of the chart of Fig. 9, itis to be tted either with an air conduction receiver or a boneconduction receiver of the type indicated between the boundary lines 54,55 and with an instrument having a tone control setting likewiseindicated between the boundary lines 54, 55. It will be noted that undercolumn A of air conduction receivers, there is the legend IU-L overIIJ-W in the area between the two boundary lines 54, 55. This indicatesthat the particular person may be fitted either with a receiver havingthe response curve Ill-L of Fig. 3 or with a receiver having a responsecurve lil-W o1 Fig. 3.

If the threshold curve extends below the boundary line 55, then the usershould be tted either with an air conduction receiver or a boneconduction receiver indicated on chart 9 by the legend below theboundary line 55 and by an instrument having tone controls likewiseindicated on the chart of Fig. 9 below the boundary line 55. The chartof Fig. 9 also shows an additional boundary line 55 which is lower thanthe boundary line 55 to indicate that if the threshold of hearing of theear to be tted extends below the line 55, it should be tted withreceivers and tone settings indicated by the legends below line 55.

summarizing, the tting chart described above in connection with Fig. 11,is designed for cooperation with audiogram charts showing the hearingloss of the user, of the type described in connection with Figs. 1 and 2and has aligning data which makes it possible to align the chart withthe data of the audiogram, the fitting chart being made of transparentmaterial so that when it is superimposed on the audiogram the audiogramdata and curves are not obscured by it. The fitting chart has aplurality of boundary lines and instrument data so correlated t theperformance characteristics of the component parts and the overallperformance of the instrument data associated with the boundary linesand arranged for cooperation with the data of the audiogram chart, sothat the relationship of the audio-metric curve elements of the earwhich is to be tted, as shown in the audiogram chart, to the boundarylines of the fitting chart, indicates which combination of instrumentcomponents and instrument settings will best t the needs of the user.

The chart of Fig. 12 has likewise formed thereon a boundary outlinecorresponding to the boundary outline of the audiogram, having thereonan area indicated by dash lines 6|, the level and frequency region ofunvoiced consonants of speech, an area indicated by a dash-dot line 62,the level and frequency region of voiced consonants of speech, and anarea indicated by the dash double-dot line 63, the level and frequencyregion of the vowel sounds of speech. By placing such transparentoutline chart of the type shown in Fig. 12A on an audiogram, it ispossible to determine at a glance what type of speech sounds the personhaving a particular type of impairment, as indicated by his thresholdcurve corresponding to curve 2l of Fig. 1, and that he will partiallyhear the vowel sounds and voiced consonants.

Similarly, by placing the chart of Fig. 12 over the audiogram of Fig. 2,it will indicate that only the vowel sounds will be heard by a personhaving a hearing loss as represented by air conduction threshold 24 inFig. 2, but he will not hear 8 the voiced consonants or the unvoicedconsonants of speech.

It will be apparent to those skilled in the art that the novelprinciples of the invention disclosed herein in connection with specicexemplications thereof will suggest various other modifications andapplications `of the same. It is accordingly desired that in construingthe breadth of the appended claims they shall not be limited to thespecific exemplications of the invention described above.

I claim:

1. In a system for fitting hearing aid instruments of predeterminedcomponent and overall performance characteristics in accordance with thehearing loss of the user as indicated by audio--l metric curves of thethreshold of hearing on an audiogram chart having a frequency scale anda hearing loss scale: a scale member of sheet material provided 'with`a. transparent scale region having a, complementary scale correspondingto the loss scale of the chart; and an ear selector mark so placed onthe complementary scale of the scale member that when the scale memberis placed in a predetermined position on the chart, the relationship ofthe selector mark to the curve data of the chart will indicate whetherthe hearing aid is to be tted to the better ear or to the poorer ear ofthe user.

2. In a system for tting hearing aid instruments of predeterminedcomponent and overall performance characteristics in accordance with thehearing loss of the user as indicated by audiometric curves of thethreshold of hearing on an audiogram chart having a frequency scale anda hearing loss scale: a scale member of sheet material provided with atransparent scale region having a complementary scale shorter than theloss scale of the audiogram and a graduation so correlated to saidperformance characteristics and the audiometric curves that when saidscale mem-` ber is placed in a, predetermined position on the audiogramchart the relationship of the elements of the complementary scale to thedata of the audiogram chart will indicate whether the user is to befitted with a bone conduction instrument or an air conductioninstrument.

3. In a system for fitting hearing aid instruments of predeterminedcomponent and overall performance characteristics in accordance with thehearing loss of the user as indicated by audiometric curves of thethreshold of hearing on an audiogram chart having a frequency scale anda hearing loss scale: slider scale means having two relatively movableslider members yof sheet material each having a transparent region; thetransparent region of one slider member having a first scalecorresponding to the loss scale of the chart; and an ear selector markso placed on said loss scale that when the slider is placed in apredetermined position on the chart the relationship of the selectormark to the curve data of the chart will indicate whether the hearingaid is to be fitted to the better eer or to the poorer ear of the user;the transparent region of the other slider member having a second scaleshorter than the rst scale and a graduation so correlated to saidperformance characteristics and the audiometric curves that when saidother slider is placed in a predetermined position on the audiogramchart the relationship of the elements of the second scale to the dataof the audiogram chart will indicate whether the user is to be tted witha bone conduction instrument or an air conduction instrument.

4. In a system for determining the effect of the hearing loss ofdeafened person on his perception of speech: an audiograrn chart havinga frequency scale and a, hearing loss scale for indicating thereon by anaudiometric hearing-loss curve the threshold of hearing of a person, andin conibination therewith an additional chart of transparent sheetmaterial having aligning indications for aligning the additional chartwith the scales of the audiogram chart, said additional chart having aplurality of different boundary lines bounding areas corresponding tothe level and frequency distribution of unvoiced consonants of speech,of voiced consonants of speech and of vowel sounds of speech, saiddiierent boundary 15 1,608,043

lines being arranged so that when the additional chart is superposedover an audiograin chart, the relation of the hearing-loss curve to saiddif- REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date 535,375 Hill Mar. 12, 18951,528,944 Newell Mar. 10, 1925 Smith Nov. 23, 1926- 2,003,875 Balbi June4, 1935 2,112,569 Lyborger Mar. 29, 1938

